The last batch had reduced boiler mountings and detail differences to the cab to conform to the new LNER loading gauge. These were classified B7/2. The earlier batches were classified B7/1.

Thirty-eight locomotives passed to British Railways in 1948, but withdrawal began soon afterwards. Some locomotives surviving in 1949 were renumbered between 61702 and 61713 to make more room for Thompson Class B1 locomotives then under construction.